mineral
Tumbled smoky quartz
Quartz (SiO₂), smoky variety
AI-generated identification · may be incorrectBrown-gray, translucent to opaque, with a vitreous luster and irregular fractures; Mohs hardness 7, trigonal crystal structure, and no cleavage. The rounded shape and polish indicate tumbling; the dark spots may be inclusions or surface pits.
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Physical properties
Brown-gray, translucent to opaque, with a vitreous luster and irregular fractures; Mohs hardness 7, trigonal crystal structure, and no cleavage. The rounded shape and polish indicate tumbling; the dark spots may be inclusions or surface pits.
Formation & geological history
Quartz crystallizes from silica-rich fluids in veins and cavities, commonly in granitic rocks and pegmatites. Smoky coloration results from natural irradiation acting on trace aluminum; the image does not establish the specimen’s age or locality.
Uses & applications
Used as an ornamental and jewelry stone, and collected as a common quartz variety.
Geological facts
Quartz is abundant in Earth’s crust; smoky color can range from pale gray to nearly black.
Field identification & locations
Identify by its hardness, glassy luster, and lack of cleavage; smoky quartz occurs worldwide, including Brazil, the Alps, and the United States. A small tumbled specimen typically sells for about $1–$10.
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Sandstone (with potential mineral staining/concretions)
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Granite, a coarse-grained felsic intrusive igneous rock
igneous
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Pegmatite with Tourmaline and Quartz
Igneous Pegmatite
igneous
Granite
Granite (Phaneritic intrusive igneous rock)
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